add support for GCC 6.4.0

GCC 6.4.0 has one big advantage over 6.3.0: it is shipped as .tar.xz,
shaving 30 MB from its download size, and also considerably speeding
up the extraction process.

All patches are symlinks to the GCC 6.3.0 ones, except 0004-posix_memalign.diff
which was rebased to apply cleanly.
0014-ubsan-empty-string-fix.diff was removed, since it was upstreamed.

hashes/gcc-6.4.0.tar.xz.sha1

@@ -0,0 +1 @@
+f237974b2d3af0f60936ce6a2f35b912a91e0239  gcc-6.4.0.tar.xz

patches/gcc-6.4.0/0001-linux_libc_has_function.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0001-linux_libc_has_function.diff

patches/gcc-6.4.0/0002-ssp_nonshared.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0002-ssp_nonshared.diff

patches/gcc-6.4.0/0003-mips-unwind.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0003-mips-unwind.diff

patches/gcc-6.4.0/0004-posix_memalign.diff

@@ -0,0 +1,30 @@
+diff --git a/gcc/config/i386/pmm_malloc.h b/gcc/config/i386/pmm_malloc.h
+index a9c2be4..2596a90 100644
+--- a/gcc/config/i386/pmm_malloc.h
++++ b/gcc/config/i386/pmm_malloc.h
+@@ -27,12 +27,13 @@
+ #include <stdlib.h>
+ 
+ /* We can't depend on <stdlib.h> since the prototype of posix_memalign
+-   may not be visible.  */
++   may not be visible and we can't pollute the namespace either.  */
+ #ifndef __cplusplus
+-extern int posix_memalign (void **, size_t, size_t);
++extern int _mm_posix_memalign (void **, size_t, size_t)
+ #else
+-extern "C" int posix_memalign (void **, size_t, size_t) throw ();
++extern "C" int _mm_posix_memalign (void **, size_t, size_t) throw ()
+ #endif
++__asm__("posix_memalign");
+ 
+ static __inline void *
+ _mm_malloc (size_t __size, size_t __alignment)
+@@ -42,7 +43,7 @@ _mm_malloc (size_t __size, size_t __alignment)
+     return malloc (__size);
+   if (__alignment == 2 || (sizeof (void *) == 8 && __alignment == 4))
+     __alignment = sizeof (void *);
+-  if (posix_memalign (&__ptr, __alignment, __size) == 0)
++  if (_mm_posix_memalign (&__ptr, __alignment, __size) == 0)
+     return __ptr;
+   else
+     return NULL;

patches/gcc-6.4.0/0005-cilkrts.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0005-cilkrts.diff

patches/gcc-6.4.0/0006-libatomic-test-fix.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0006-libatomic-test-fix.diff

patches/gcc-6.4.0/0007-libgomp-test-fix.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0007-libgomp-test-fix.diff

patches/gcc-6.4.0/0008-libitm-test-fix.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0008-libitm-test-fix.diff

patches/gcc-6.4.0/0009-libvtv-test-fix.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0009-libvtv-test-fix.diff

patches/gcc-6.4.0/0010-static-pie-support.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0010-static-pie-support.diff

patches/gcc-6.4.0/0011-j2.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0011-j2.diff

patches/gcc-6.4.0/0012-s390x-muslldso.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0012-s390x-muslldso.diff

patches/gcc-6.4.0/0013-microblaze-pr65649.diff

@@ -0,0 +1 @@
+../gcc-6.3.0/0013-microblaze-pr65649.diff